Seizures may be treated using cranial nerve stimulation (CNS). CNS includes application of an electrical stimulation signal to a cranial nerve, e.g., vagus nerve, of a patient. When the cranial nerve is a vagus nerve, CNS is referred to as vagus nerve stimulation (VNS).
When used to treat seizure disorders, conventional VNS attempts to decrease synchronization of a patient's interconnected cortical regions and/or reduces the duration, spatial spread or severity of seizures. VNS in the treatment of seizure disorders typically uses a pattern of charge-balanced constant current stimulation at stimulus frequencies of 20-30 Hz. Although VNS has proven to be an effective adjunctive treatment for refractory epilepsy, some patients do not respond to the conventional paradigm of VNS therapy or become unresponsive to the therapy over time.